1. Field of the Invention
The invention relates to a closing cylinder, in particular, for vehicles, for actuating a lock and/or a switch by means of a key inserted into a key channel:
2. Discussion of the Related Art
In the known closing cylinder of this kind the cylinder core, which is rotatably received in the cylinder housing, has a profiled axial bore and in the axial bore several successively arranged rotary disks are provided which function as tumblers. These rotary disks are loose and have central openings which determine the key channel. The key has radial cuts with defined control shoulders while the profiled central opening has counter shoulders. The rotary disks have a circular profiled disk contour with a radial cutout and with a locking surface delimiting the radial cutout. Moreover, the closing cylinder has an axis-parallel, loose locking member, which is, in particular, embodied as a roll body and is always guided with a partial cross-section within a radial penetration of the hollow cylindrical cylinder core. In an initial rotational position of the cylinder core, in which the insertion and removal of the key is possible, the locking member engages with a remaining cross-section an axial inner groove of the cylinder housing. In this initial rotational position the locking member is radially supported by the peripheral locking surface of the rotating disk so that a rotation of the cylinder core is impossible. When, however, the rotary disk is moved by actuation of the key in the direction of a working rotational position of the cylinder core, the edge cutout of the rotary disk is aligned with the locking member and serves for receiving the remaining cross-section of the locking member while the inner groove of the cylinder housing comes free from the locking member.
The disadvantage of the known closing cylinder of this kind is that in it the cylinder core can be moved, without the proper key, by a so-called xe2x80x9cpicking methodxe2x80x9d with burglary tools from the locking-active initial rotational position into a working rotational position of the cylinder core in which the lock which is provided with such a closing cylinder can be opened. In this picking method the individual rotary disks are rotated by a pin until the edge cutouts provided on their disk contour are aligned with the axis-parallel locking member so that a coupling connection between the rotary disks and the cylinder core is realized. Then, a rotation action exerted onto the rotary disks can move the cylinder core and transfer it into its working rotational position.
In a known closing cylinder (DE 39 24 971 A1) each one of the rotary disks is provided with a radial nose which is positioned between the two legs of a return spring. The legs of the return spring penetrate two sector-shaped peripheral cutouts in the individual rotary disks. They serve for providing a return movement of the return spring into an initial rotational position, independent of whether the rotary disks have been turned by the key in the clockwise or counter-clockwise direction. The return spring requires because of the peripheral sector cutouts in the rotary disks a considerable amount of space. The anti-burglary safety with respect to the aforementioned picking method cannot be improved by means of the return spring.
The invention has the object to develop a burglary-proof closing cylinder of the aforementioned kind. This is achieved according to the invention by the features which will be explained in more detail in the following.
In the invention, the spring member has approximately an L-shaped axial profile. With one of its L-legs it is positioned in a radial cutout of the cylinder core which is connected via a radial slot with the axial bore of the cylinder core. The other L-leg of the spring member according to the invention projects through this radial slot radially inwardly and supports itself therein on a shoulder of at least one of the rotary disks. When it is attempted to slide the rotary disks according to the picking method, it is necessary to perform a work against the spring load. As soon as the rotary disk is released by the burglary tool, it rotates back into its locking position. The cutout in the cylinder core can be arranged in the peripheral area of the annular cylinder core. The radially inwardly projecting leg can have a very small leg thickness. This results in an extremely space-saving arrangement for the spring member. The shoulder for supporting the radial leg of the spring member can advantageously be the radial shoulder of the rotary disk which serves for entraining the cylinder core upon key rotation of the rotary disks. For this entrainment the cylinder core is provided with an inner radial counter shoulder.